The principle investigator for this proposal, Dr. Yaming Wang, is an Instructor in Anesthesia at Brigham and Women's Hospital and Harvard Medical School. The work outlined in this proposal will serve to fund the mentored transition of Dr. Wang into gene therapy of muscular diseases and from a research associate to an independent academic investigator and application R01 level funding. The mentor in this proposal, Dr. Allen is an independent clinical scientist with extensive published experience in the area of muscle biology. A mentor committee consisting of Dr. Allen and three other scientists (Dr. Breakefield, Dr. Kunkle, and Dr. Leboulch) will serve as the advisory committee for Dr. Wang and will carefully oversee her progress. The environment in which the proposed work will be carried out (Harvard Medical School) is a world class scientific community where biomedical research is performed at the highest level with intimate associations between clinical and basic science disciplines. In this proposal, Dr. Wang will investigate the effectiveness of an exciting novel hybrid HSV/AAV amplicon virion expressing dystrophin as a possible solution to the problems facing the currently proposed and active gene therapy protocols for a common X-linked myopathy, Duchenne's Muscular Dystrophy (DMD). Current therapy has failed because it has been unsuccessful in obtaining durable expression of the transferred gene product. There were a number of reasons for this failure, such as cytotoxicity, immune reactions caused by with viral gene expression and virion proteins, and non-integration of vector DNA. She has demonstrated that the HSV-1 amplicon virions are capable of transducing skeletal muscle myofibers in vivo and myoblasts and myotubes in vitro using both GFP and dystrophin as the experimental marker gene. Both GFP and dystrophin virions were shown to permanently transduce myoblasts in culture at a low frequency (0.5-2 percent) suggesting their ability to integrate into the host genome. As a work in progress she has designed new amplicon vectors capable of carrying the 14kB dystrophin cDNA, GFP and an antibiotic selection marker, and has demonstrated that these amplicons can be packaged into HSV virion particles that can induce transcription of the appropriate protein in mdx myotubes. The overall aim of this project is to create a new nontoxic, high efficiency and long term transgene expression AAV/HSV-1 hybrid vector system to express dystrophin in a mdx mouse animal model to attempt DMD phenotype correction.